From owner-freebsd-net@freebsd.org Thu Jan 16 16:35:18 2020 Return-Path: Delivered-To: freebsd-net@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 6A5501EE5C0 for ; Thu, 16 Jan 2020 16:35:18 +0000 (UTC) (envelope-from eugen@grosbein.net) Received: from hz.grosbein.net (hz.grosbein.net [IPv6:2a01:4f8:c2c:26d8::2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "hz.grosbein.net", Issuer "hz.grosbein.net" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 47z8tr6qHfz4G0W; Thu, 16 Jan 2020 16:35:16 +0000 (UTC) (envelope-from eugen@grosbein.net) Received: from eg.sd.rdtc.ru (eg.sd.rdtc.ru [IPv6:2a03:3100:c:13:0:0:0:5]) by hz.grosbein.net (8.15.2/8.15.2) with ESMTPS id 00GGZ5ZS027618 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 16 Jan 2020 16:35:06 GMT (envelope-from eugen@grosbein.net) X-Envelope-From: eugen@grosbein.net X-Envelope-To: vas@sibptus.ru Received: from [10.58.0.4] ([10.58.0.4]) by eg.sd.rdtc.ru (8.15.2/8.15.2) with ESMTPS id 00GGZ2LA033141 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT); Thu, 16 Jan 2020 23:35:02 +0700 (+07) (envelope-from eugen@grosbein.net) Subject: Re: IPSec transport mode, mtu, fragmentation... To: Victor Sudakov References: <20191220152314.GA55278@admin.sibptus.ru> <4cc83b85-dd30-8c0d-330e-aa549ce98c98@yandex.ru> <20200116155305.GA465@admin.sibptus.ru> <55f7bafa-24c4-9810-0d21-f82cb332ee2d@grosbein.net> <20200116160745.GA1356@admin.sibptus.ru> Cc: freebsd-net@freebsd.org, "Andrey V. Elsukov" , Michael Tuexen From: Eugene Grosbein Message-ID: <72355e03-1cf8-c58f-3aec-b0a21e631870@grosbein.net> Date: Thu, 16 Jan 2020 23:34:56 +0700 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20200116160745.GA1356@admin.sibptus.ru> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=0.3 required=5.0 tests=BAYES_00,LOCAL_FROM, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.2 X-Spam-Report: * -2.3 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record * -0.0 SPF_PASS SPF: sender matches SPF record * 2.6 LOCAL_FROM From my domains X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on hz.grosbein.net X-Rspamd-Queue-Id: 47z8tr6qHfz4G0W X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=permerror (mx1.freebsd.org: domain of eugen@grosbein.net uses mechanism not recognized by this client) smtp.mailfrom=eugen@grosbein.net X-Spamd-Result: default: False [-3.86 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-0.999,0]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; TO_DN_SOME(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[grosbein.net]; RCVD_COUNT_THREE(0.00)[3]; TO_MATCH_ENVRCPT_SOME(0.00)[]; R_SPF_PERMFAIL(0.00)[]; IP_SCORE(-1.76)[ip: (-4.80), ipnet: 2a01:4f8::/29(-2.48), asn: 24940(-1.51), country: DE(-0.02)]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:24940, ipnet:2a01:4f8::/29, country:DE]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[] X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Jan 2020 16:35:18 -0000 16.01.2020 23:07, Victor Sudakov wrote: >>> What beats me is that I cannot reproduce this problem in bhyve. In this >>> packet dump: http://admin.sibptus.ru/~vas/ipsec1.pcap.gz I'm scp-ing a >>> 50M file from 192.168.246.10 (bhyve guest) to 192.168.246.1 (bhyve >>> host), and I see no fragments, and the largets packet is 1466 bytes, and >>> the scp never stalls nor fails. >>> >>> Why is it NOT broken this time? >>> >>> Both hosts are 12.1-RELEASE-p1. >> >> I could not reproduce the problem with unpatched recent stable/11, either :-) > > Is there a way to view the MSS in the TCP segments before encryption or > after decryption? I want to compare them in situations with IPSec > enabled and disabled. > > I've never been able to see anything in "tcpdump -i enc0", probably it > cannot do transport mode IPSec because the man page talks about "outer > and inner header." enc0 does what you need but before you use it, remember: 1) before starting, you better change sysctls to: net.enc.in.ipsec_filter_mask=0 net.enc.out.ipsec_filter_mask=0 so using enc0 does not pass packets over netpfilter rules extra time; 2) don't forget: ifconfig enc0 up 3) tcpdump has no means to filter by inner attributes in case of tunnel mode; it still shows decoded IPSec transport mode packets correctly.